1. Field of the Invention
The present invention relates to a matting agent suitable for paint, etc.
2. Description of the Prior Art
In recent years, consumers' liking for paint has become diversified, and as a tendency to this, preference is now given to painted films of medium or low luster or subdued color over those to highly lustrous color.
Up to this time, in order to impart a matting effect to paints. various solid additives have been added to paints as a matting agent. For example, there have been employed inorganic pigments, typical of which are calcium carbonate and silicon compounds, and inorganic materials such as glass fibers. However, painted films to which solid additives are added are flat and short of massive feel, and are poor in design effect. Moreover, in respect to the properties of the painted film, the hardness of the painted film becomes high by mixing inorganic material, and when the particle diameter of the inorganic material is larger than about 10 .mu., there occurs a tendency to lower the resistance to abrasion and the resistance to damage, on account of brittleness which is a characteristic of the inorganic material itself. Furthermore, because of the low adhesiveness of the inorganic material, which is a matting agent, to the organic matrix resin, and further because the inorganic material itself is not ductile, the processability of the painted film is lowered.
To remedy such shortcomings, a method is proposed which uses particles of a thermoplastic organic polymer such as polyethylene, polypropylene, polyester, etc. But these matting agents are poor in adhesiveness to paints and in resistance to solvents, and when melted, the matting effect is decreased. On the other hand, among organic polymer particles, acrylonitrile (hereinafter referred to as AN) polymer particles in particular, have various favorable properties such as excellent resistance to and weathering, resistance to solvents, and hence are desirable as a matting agent. But the AN polymer particles obtained by the usual polymerization methods such as aqueous precipitation polymerization, melt polymerization, and bulk polymerization, are irregular in shape and size, or porous. Consequently, it has been difficult to obtain an even painted surface from paints to which these AN polymer particles have been added.
To solve such problems, in Japanese Patent Kokai (Laid-open) Nos. 106269/1980 and 126863/1982 for example, methods have been proposed wherein AN polymers of uniform particle shape and size are used. By such methods, the matting effect can be improved, but the production of such AN polymer globular particles involves complicated operations and process steps.
Under such circumstances, we eagerly carried out research, as a a result, we found that by using AN fibers of extremely short fiber lengths as a matting agent, it is possible to provide a matting agent which has not difficulties in production, is excellent in design effect, and can exhibit resistance to weathering, resistance to solvents and good adhesiveness. This finding led to the present invention.
The object of the present invention is therefore to provide a matting agent in an industrially advantageous manner which is excellent in design effect, resistance to weathering, resistance to solvents, and adhesiveness, and is free from problems in practical use.